The human visual processing involves complex actions and interactions of the eyes and the brain. To simplify this description, we can think of the visual system as being composed of three areas of function, namely, acuity, perception, and eye movement. Any one of these functions can be impaired without impairment to the remaining two functions or combinations of impairments may arise from a variety of factors including genetics, disease, and health issues such as heart attacks through to mild traumatic brain injuries.
Visual acuity, commonly refers to the clarity of vision and is similarly dependent upon a combination of optical and neural factors, as is the visual system overall, including for example, the sharpness of the retinal focus within the eye, the health and functioning of the retina, and the sensitivity of the interpretative faculty of the brain. A common cause of low visual acuity is refractive error (ametropia) which can arise from a variety of factors leading to conditions such as pseudomyopia, myopia, and hyperopia whilst optical causes may include astigmatism or more complex corneal irregularities. Typically, such issues are addressed by optical means such as eyeglasses, contact lenses, laser surgery, etc.
Neural factors that limit acuity are located in the retina, the brain, or the pathway connecting them, the optical nerve. Examples for the first are a detached retina and macular degeneration, to name just two, whilst in other cases, low visual acuity is caused by brain damage, such as from traumatic brain injury or stroke. A common impairment is amblyopia resulting from incorrect nerve pathway function connecting the eye with the brain which results in decreased vision in an eye that otherwise appears normal or the decrease is out of proportion to any associated structural problems of the eye. Amblyopia has been classically treated by patching the fellow eye to force use of the amblyopic eye. However, many individuals, especially those who only have a mild form, are not even aware they have the condition until tested at older ages, since the vision in their stronger eye is normal. Individuals with severe amblyopia, however, may experience related visual disorders, including poor depth perception, poor visual acuity, poor spatial acuity, low sensitivity to contrast and motion. Amblyopia is characterized by several functional abnormalities in spatial vision, including reductions in visual acuity (VA), contrast sensitivity function (CSF), and Vernier acuity as well as spatial distortion, abnormal spatial interactions, and impaired contour detection. In addition, individuals with amblyopia suffer from binocular abnormalities such as impaired stereoacuity (stereoscopic acuity) and abnormal binocular summation.
Within the prior art there is an increasing understanding of the role of binocular dysfunction (suppression) in amblyopia that has motivated a reformulation of amblyopia treatment. Many amblyopic patients have a structurally intact binocular visual system that can be revealed by decreasing the fellow-eye contrast to reduce interocular suppression. Accordingly, repeated active dichoptic perceptual-learning tasks or dichoptic game play have been shown to significantly improve visual acuity of amblyopic children and adults. Such dichoptic tasks and games provide contrast-balanced binocular vision, with low contrast for the fellow eye and high contrast for the amblyopic eye. However, these dichoptic perceptual learning tasks are intensive and repetitive and the dichoptic games used to date have limited appeal resulting in approximately 40% of unsupervised patients becoming non-compliant with even only 16 hours of assigned activity over a 4 week period.
Accordingly, it would be beneficial to provide a method or system that provides the required dichoptic perceptual learning but in a manner that the user maintains its use and compliance is increased. It would be further beneficial to provide this method or system in a manner that the user performs tasks in a normal manner and “forgets” that they are actually undergoing treatment as it is integrated with minimal disruption to their lift and activities. Accordingly, the inventors have established a methodology exploiting complementary dichoptic stimulation for addressing binocular amblyopia within normal environments through their use of display devices in their everyday activities.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.